diff --git a/src/DynamicModel.cc b/src/DynamicModel.cc
index c0177d18e0007b66f5afbdbe204d4a120887b01d..7c25804a8b8c4cef5524c8507f29965c74eb51dd 100644
--- a/src/DynamicModel.cc
+++ b/src/DynamicModel.cc
@@ -7179,3 +7179,15 @@ DynamicModel::substituteVarExpectation(const map<string, expr_t> &subst_table)
   for (auto &equation : equations)
     equation = dynamic_cast<BinaryOpNode *>(equation->substituteVarExpectation(subst_table));
 }
+
+void
+DynamicModel::checkNoRemainingPacExpectation() const
+{
+  for (size_t eq = 0; eq < equations.size(); eq++)
+    if (equations[eq]->containsPacExpectation())
+      {
+        cerr << "ERROR: in equation " << equation_tags.getTagValueByEqnAndKey(eq, "name")
+             << ", the pac_expectation operator references an unknown pac_model" << endl;
+        exit(EXIT_FAILURE);
+      }
+}
diff --git a/src/DynamicModel.hh b/src/DynamicModel.hh
index 1fd3caf0d7788c77e4ff6940dc790f6ace68ad7d..51b5fae1f8994ec4e31307e6c4e0b241ad7ada99 100644
--- a/src/DynamicModel.hh
+++ b/src/DynamicModel.hh
@@ -557,6 +557,10 @@ public:
   //! Fills eval context with values of model local variables and auxiliary variables
   void fillEvalContext(eval_context_t &eval_context) const;
 
+  /*! Checks that all pac_expectation operators have been substituted, error
+    out otherwise */
+  void checkNoRemainingPacExpectation() const;
+
   auto
   getStaticOnlyEquationsInfo() const
   {
diff --git a/src/ModFile.cc b/src/ModFile.cc
index 049ac4563719100894ef8d5731fb7f3b96a4031b..cf940e5f033943a3db03b0c9937cbfe68ff5b034 100644
--- a/src/ModFile.cc
+++ b/src/ModFile.cc
@@ -502,6 +502,7 @@ ModFile::transformPass(bool nostrict, bool stochastic, bool compute_xrefs, bool
                                          eqtag_and_lag, nonstationary, pms->growth);
         dynamic_model.substitutePacExpectation(pms->name);
       }
+  dynamic_model.checkNoRemainingPacExpectation();
 
   dynamic_model.addEquationsForVar();